Replace magic numbers with named constants

Replaced hardcoded values 64 and 1000 with descriptive constants:
- BUFFER_SAFETY_MARGIN (64): Extra space for string operations
- MAX_PAREN_SEARCH_DISTANCE (1000): Prevent runaway parsing

Improves code readability and maintainability.

Author: wqxoxo

db/db_sqlite3.c

@@ -9,6 +9,10 @@
 #if HAVE_SQLITE3
   #include <sqlite3.h>
 
+/* Constants for SQL processing limits */
+#define BUFFER_SAFETY_MARGIN 64           /* Extra space for string operations */
+#define MAX_PAREN_SEARCH_DISTANCE 1000    /* Prevent runaway parsing */
+
 struct db_sqlite3 {
 	/* The actual db connection.  */
 	sqlite3 *conn;
@@ -284,7 +288,7 @@ static char *normalize_varchar_to_text(const tal_t *ctx, const char *query)
 
 	/* INT(3) -> INTEGER(7) worst case: +4 bytes per conversion */
 	size_t max_expansions = (query_len / 3) * 4;
-	size_t buffer_size = query_len + max_expansions + 64;
+	size_t buffer_size = query_len + max_expansions + BUFFER_SAFETY_MARGIN;
 
 	if (buffer_size < query_len)
 		return NULL;
@@ -310,7 +314,7 @@ static char *normalize_varchar_to_text(const tal_t *ctx, const char *query)
 				while (*src && *src != ')') {
 					src++;
 					/* Prevent runaway on malformed SQL */
-					if (src - paren_start > 1000)
+					if (src - paren_start > MAX_PAREN_SEARCH_DISTANCE)
 						return NULL;
 				}
 				if (*src == ')') src++;